Pistons employed in internal combustion engine applications must withstand high temperatures. To reduce the temperature of piston components, especially adjacent the combustion chamber, a cooling gallery may be provided within the piston crown. The cooling gallery is typically formed by an interior volume located within the piston crown and is covered with a piston crown bottom cover. The piston crown bottom cover is typically located along a lower surface of the piston crown.
A nozzle directing a flow of oil to the cooling gallery is typically located between the piston ring belt portion and the piston skirt. The oil flows into the cooling gallery through an aperture in the piston. The reciprocating motion of the piston generally moves the oil back and forth within the piston cooling gallery, thereby removing at least part of the heat of the piston ring belt portion and the combustion chamber. The heated oil typically exits the cooling gallery through the aperture located between the piston ring belt portion and the piston skirt and/or one or more auxiliary drain apertures, while fresh oil is supplied by the nozzle.
Internal combustion engines, particularly heavy-duty diesel engines, include stringent cooling requirements due to the elevated combustion pressure and temperature within the combustion chamber. Moreover, to improve engine performance it has become increasingly desirable to operate engines at even higher combustion pressures and temperatures. Unfortunately, the existing cooling gallery formed inside of the interior volume of the piston crown may not always be able to meet the increasing cooling requirements needed.
Accordingly, there exists a need for a piston lubrication system that will provide enhanced cooling properties when compared to the current piston lubrication systems that are available today.